A known laser scanning microscope in the related art uses an integrator circuit to amplify an electrical signal to obtain a signal (for example, see PTL 1). By using the integrator circuit, an image with a high SN ratio can be obtained even when light coming from a specimen is faint. Furthermore, by adjusting the offset of a black level signal, the contrast can be adjusted such that the light coming from the specimen is displayed with the optimum brightness in an image.